A method for the rapid construction of cRNA standard curves in quantitative real-time reverse transcription polymerase chain reaction

Quantification of nucleic acids, especially of mRNA, is increasingly important in biomedical research. The recently developed quantitative real-time polymerase chain reaction (PCR) - a highly sensitive technology for the rapid, accurate and reproducible quantification of gene expression - offers major advantages over conventional quantitative PCR. Transcript quantification is performed in the exponential phase of the PCR reaction through extrapolation of fluorescence signals from a standard calibration curve which represents the initial copy number for a given fluorescence signal. We have developed a method for gene transcript quantification which is based on a LightCycler - assisted real-time PCR in combination with a simple and rapid approach for the construction of external cRNA standards with identical gene sequences as the target gene. Synthesis of cRNAs was performed by in vitro transcription with T7 RNA polymerase followed by reverse transcription and real-time PCR. We applied this approach for transcript quantification of eukaryotic initiation factor 3 p110 (EIF3S8) mRNA in normal testicular tissue. We also present a rapid and simple strategy for the construction of cRNA standards for use in real-time PCR.

[Model fluids of blood for in vitro testing of artificial heart valves]

The increasing development and implantation of artificial organs subject to perfusion with human blood once implanted (grafts, heart-valve prostheses and assist systems) require extensive testing of hydrodynamic performance in mock circulation models. As human blood ist not always available in the necessary quantities, different fluids (water, saline or glycerine solutions) are employed for measurements of flow characteristics. However, these model fluids do not possess the non-Newtonian rheological properties of blood. In addition, they do not allow estimation of possible blood damage. Aqueous solutions of high molecular weight polyacrylamides (PAA) have rheological properties similar to blood, displaying also molecular degradation due to shear stress in the flow. Therefore, they were used as model fluid for blood. Different model solutions were compared to blood with regard to their influence on characteristic flow parameters of mechanical heart valves. Likewise, the shear damage of erythrocytes could be compared to flow-induced polymer degradation. It was shown that PAA solutions in definite concentrations are suitable models for blood, not only in terms of non-Newtonian rheology, but also in terms of estimation of hemolytic potential of artificial heart valves.

Identification and biochemical characterization of Arabidopsis thaliana sulfite oxidase. A new player in plant sulfur metabolism

In mammals and birds, sulfite oxidase (SO) is a homodimeric molybdenum enzyme consisting of an N-terminal heme domain and a C-terminal molybdenum domain (EC ). In plants, the existence of SO has not yet been demonstrated, while sulfite reductase as part of sulfur assimilation is well characterized. Here we report the cloning of a plant sulfite oxidase gene from Arabidopsis thaliana and the biochemical characterization of the encoded protein (At-SO). At-SO is a molybdenum enzyme with molybdopterin as an organic component of the molybdenum cofactor. In contrast to homologous animal enzymes, At-SO lacks the heme domain, which is evident both from the amino acid sequence and from its enzymological and spectral properties. Thus, among eukaryotes, At-SO is the only molybdenum enzyme yet described possessing no redox-active centers other than the molybdenum. UV-visible and EPR spectra as well as apparent K(m) values are presented and compared with the hepatic enzyme. Subcellular analysis of crude cell extracts showed that SO was mostly found in the peroxisomal fraction. In molybdenum cofactor mutants, the activity of SO was strongly reduced. Using antibodies directed against At-SO, we show that a cross-reacting protein of similar size occurs in a wide range of plant species, including both herbacious and woody plants.

Dynamics of chronic active herpesvirus-6 infection in patients with chronic fatigue syndrome: data acquisition for computer modeling

Ten adult patients with persistent active HHV-6 variant A infection and clinical chronic fatigue syndrome (CFS) were studied over a period of 24 months after initial clinical diagnosis. CFS was diagnosed according to IIIP-revised CDC-criteria as defined by the CFS Expert Advisory Group to the German Federal Ministry of Health in 1994. Changes in HHV-6 antibody titer, viral DNA load, peripheral blood T lymphocytes and subpopulations, as well as CD4/CD8 cell ratio and cell death (apoptosis) were monitored. Data were collected for comparison with respective changes in acute HHV-6 infection and as a basis for future computer simulation studies. The results showed variable but slightly elevated numbers of HHV-6 DNA copies in the blood of patients with CFS, while PBL (peripheral blood lymphocyte) apoptosis rates were clearly increased. CD4/CD8 cell ratios varied from below 1 up to values as seen in autoimmune disorders. Contrary to acute HHV-6 infection, T lymphocytes do not exhibit the usual response to HHV-6, that is elevation of mature and immature populations suggesting a certain degree of unresponsiveness. The data suggest that persistent low-dose stimulation by HHV-6 may favor imbalanced immune response rather than overt immune deficiency. This hypothesis requires confirmation through additional functional studies.

Dynamics of active progressive infection with HIV1: data acquisition for computer modeling

Nineteen adult patients with progressive HIV1 infection, which progressed within 5 years from acute HIV syndrome to final AIDS were studied. Changes in HIV antibody titer, viral RNA load, peripheral T lymphocytes and subpopulations as well as CD4/CD8 cell ratio and cell death (apoptosis) were monitored. The data were collected for comparison with HHV-6 infection, which involves the same cell populations yet patients usually recover, and to serve as a further basis for future computer simulation studies. The results showed progressive increases of viral RNA copies in the patients' plasma even during clinical latency, which correlates with lymphocyte apoptosis and CD4 cell loss. Besides apparent direct CD4 cell destruction, there was indication of a disturbed intrathymic T cell differentiation. Pathologic cell changes in HIV infection continue until final death of the patient and do not return to normal after variable times as in HHV-6 infection. While HHV-6 infection can serve as models for immunostimulation, with or without immune dysregulation in computer simulation studies, HIV infection is a model for immunostimulation with final immune deficiency and cellular aplasia.

Dynamics of infection with human herpesvirus-6 in EBV-negative infectious mononucleosis: data acquisition for computer modeling

Ten adult patients with active HHV-6 variant A infections and clinical infectious mononucleosis-like disease (IM) were studied over a period of 32 weeks after onset of disease for their viral DNA load, changes in peripheral blood T-lymphocytes and subpopulations and frequency of cell death in peripheral blood cells. The data were collected as the basis for an advanced computer simulation study for which available data in the literature were too varied. Since the exact time of primary infection of the patients was not known and thus no time relationship of viral effects at cellular level were determined, we supplemented such data from separate tissue culture studies using HHV-6 alpha infection of HSB2 cells. Patients with IM demonstrate an increase in-HHV-6 DNA copies from 0 to 8.2 log 10/5 microL blood within 4 weeks return to normal by 16 weeks. Total T-lymphocytes follow infection with a 20-fold increase above normal peaking at 8-10 weeks and then return to normal by 24-28 weeks. Coincidently, less mature lymphoid cells carrying markers for stem cells, thymic cortical and medullary cells increase 8-10-fold indicating an enhanced mobilization of such cells from premature cell compartments. Cell death in peripheral mononuclear cells peaked with 30% at 8 weeks after onset of clinical disease and normalized by 24 weeks. HHV-6 replication in cell culture as determined by antigen expression, electron microscopy and harvest of infectious virus indicated a complete cycle of virus infection and replication of at least 6 days. The presented data compare well with others from the literature and will serve for testing in a computer simulation model, which is the subject of a forthcoming paper.

Real-time PCR analysis of the N-acetyltransferase NAT1 allele *3, *4, *10, *11, *14 and *17 polymorphism in squamous cell cancer of head and neck

Although tobacco smoke has been established as a main risk factor in the development of head and neck squamous cell cancer (HNSCC), genetic polymorphisms of xenobiotic metabolizing enzymes are supposed to modulate an individual's susceptibility to smoking-related HNSCC. N-acetyltransferase (NAT) 1 gene is known to be polymorphic and its protein product is implicated in the activation and detoxification of carcinogens, such as aromatic amines, present in tobacco smoke. We developed a rapid and reproducible LightCycler-assisted real-time polymerase chain reaction (PCR) for NAT1 genotyping, which allowed the parallel differentiation of NAT1*3, *4, *10 and *11 alleles and separately of NAT1*14 and *17 alleles within 60 min without the need for further post-PCR processing. In order to investigate the role of the NAT1 gene polymorphism as a risk-modifying factor in HNSCC, we tested for the presence of NAT1*3, *4, *10, *11, *14 and *17 alleles in a case-control study of 291 HNSCC patients and 300 healthy controls of Caucasian origin. Our findings suggest that in Caucasians, the risk of HNSCC is not associated with NAT1 polymorphism. The overall distribution of NAT1 allele frequencies was not significantly different among cases and controls. The presence of the fast acetylator NAT1*10 and NAT1*11 alleles did not significantly increase the risk of HNSCC and no modifying effect of NAT1*10 was observed among smokers. This new approach in NAT1 genotyping substantially increases throughput of sample analysis and, therefore, enhances opportunities to study NAT1 as a risk factor in different cancers in large-scale studies.

Carbon limitation induces sigma(S)-dependent gene expression in Pseudomonas fluorescens in soil

Recent studies employing reporter gene technology indicate that the availabilities of the major nutrients nitrogen, phosphate, and iron to Pseudomonas are not severely limited in bulk soil. Indirect evidence has pointed to carbon limitation as a severe nutritional stress in this environment. We show that a plasmid (pGM115)-borne transcriptional fusion between the sigma(S)-dependent Escherichia coli promoter P(fic) and lacZ functions as a reliable reporter for carbon availability in Pseudomonas fluorescens. When P. fluorescens strain DF57(pGM115) was introduced into bulk soil, carbon-limiting conditions were indicated by citrate-repressible induction of beta-galactosidase activity. To address carbon availability at the single-cell level, we developed an immunofluorescence double-staining procedure for individual DF57 cells expressing beta-galactosidase from P(fic). Changes in cell size and expression of beta-galactosidase were analyzed by flow cytometry. Cells extracted from soil microcosms reduced their size less than carbon-starved cells in pure culture and showed an increased tendency to aggregate. The single-cell analysis revealed that for cells residing in soil, the expression of beta-galactosidase became heterogeneous and only a DF57 subpopulation appeared to be carbon limited. In soil amended with barley straw, limited nitrogen availability has been determined by use of the bioluminescent reporter strain P. fluorescens DF57-N3. We used strain DF57-N3(pGM115) as a double reporter for carbon and nitrogen limitation that allowed us to study the dynamics of carbon and nitrogen availabilities in more detail. In straw-amended soil beta-galactosidase activity remained low, while nitrogen limitation-dependent bioluminescence appeared after a few days. Hence, nitrogen became limited under conditions where carbon resources were not completely exhausted.

A panel of Tn7-based vectors for insertion of the gfp marker gene or for delivery of cloned DNA into Gram-negative bacteria at a neutral chromosomal site

The use of Tn7-based systems for site-specific insertion of DNA into the chromosome of Gram-negative bacteria has been limited due to the lack of appropriate vectors. We therefore developed a flexible panel of Tn7 delivery vectors. In one group of vectors, the miniTn7 element, which is inserted into the chromosome, contains a multiple cloning site (MCS) and the kanamycin, streptomycin or gentamicin resistance markers. Another group of vectors intended for tagging with green fluorescent protein (GFP) carries the gfpmut3* gene controlled by the modified lac promoter PA1/04/03, several transcriptional terminators, and various resistance markers. These vectors insert Tn7 into a specific, neutral intergenic region immediately downstream of the gene encoding glucosamine-6-phosphate synthetase (GlmS) in the tested fluorescent Pseudomonas strains. The gfp-tagging vector containing a gentamicin-resistance marker is useful for tagging strains carrying a Tn5 transposon. Tn5 transposons often carry kanamycin-resistance-encoding genes and are frequently used to generate bacterial mutants and to deliver reporter constructions in gene expression studies. To demonstrate the utility of a dual marker/reporter system, the Tn7-gfp marker system was combined with a Tn5-delivered luxAB reporter system in Pseudomonas fluorescens. The system allowed detection of gfp-tagged cells in the barley rhizosphere, while expression of the Tn5-tagged locus could be determined by measuring bioluminescence.

The plasminogen activator inhibitor 1 4G/5G polymorphism is not associated with longevity: a study in octogenarians

Accumulating evidence suggests that plasma levels of the plasminogen activator inhibitor 1 (PAI-1) may modulate the risk of coronary artery disease. The regulation of PAI-1 levels underlies not only environmental but also genetic influences. The 4G/5G polymorphism of the PAI-1 gene has recently gained additional relevance as a possible cardiovascular risk factor, as the 4G allele may be associated with enhanced expression of the PAI-1 gene. This retrospective cohort study examined the effect of the PAI-1 4G/5G genotype on longevity among 205 subjects aged 80 years and older. Such studies in larger cohorts have recently become available along with new methods for the rapid and easy determination of gene polymorphisms. We utilized a light-cycler assisted method which is a fast and flexible method of analyzing the PAI-1 4G/5G polymorphism on the gene level. In these 205 persons the 4G/5G allele was found in 96 persons (47%), the 4G/4G variant in 62 (30%), and the 5G/5G allele in 47 (23%). These data are similar to the allele distribution described in other large cohorts not restricted to old age. Thus the results of this study are not suggestive of an important contribution of the PAI-1 genotype on total mortality.

Real-time genotyping of cytochrome P4501A1 A4889G and T6235C polymorphisms

Single nucleotide polymorphisms, such as the cytochrome P450 1A1 (CYP1A1) A4889G and T6235C variants, have been reported to be associated with an increased cancer risk. In order to study their role in molecular-epidemiological studies, we developed a single-step procedure for genotyping these two CYP1A1 polymorphisms using real-time polymerase chain reaction (PCR) and subsequent melting curve analysis. Genotypes of 300 unrelated Caucasians, without prior history of cancer, were determined by real-time PCR and compared to genotypes obtained by restriction fragment length polymorphism PCR. In the population examined, the allele frequency of the CYP1A1 G allele at position 4889 was 0.042, and the frequency of the T allele at position 6235 was 0.10. Five percent of samples disagreed between methods. Sequence analysis of discordant samples revealed that the differences are likely attributed to incomplete digestion of amplicons by the RFLP method. These findings confirm the reliability and utility of real-time PCR as a method for large-scale genotyping.

Mechanical degradation of polyacrylamide solutions as a model for flow induced blood damage in artificial organs

Human or animal blood is normally used as a test fluid for the in vitro evaluation of hemolysis by artificial organs. However, blood has some disadvantages (large biological variability and problems with cleaning the devices). For that reason, we searched for a reproducible technical fluid with blood-like flow characteristics that exhibits similar shear depending destruction. In this study, a direct comparison between erythrocyte damage of bovine blood and shear-induced degradation of polyacrylamide solution is given. A uniform shear field was applied to the fluids using a shear device with a plate-plate geometry. It was shown that similarities exist between erythrocytes disaggregation and breakdown of super molecular structures in polymer solutions, caused by mechanical stress. In both cases steady low shear viscositity was diminished and the elastic component of complex viscosity of blood and polymer solutions has been reduced. There is a correlation between shear-induced hemolysis of bovine blood and mechanical polymer-degradation, which depends on the applied shear stresses.

C2-ceramide and reactive oxygen species inhibit pituitary adenylate cyclase activating polypeptide (PACAP)-induced cyclic-AMP-dependent signalling pathway

The pituitary adenylate cyclase activating polypeptide (PACAP) type I receptor, a seven-domain transmembrane receptor, is positively coupled to both adenylate cyclase and phospholipase C. PACAP exerts neurotrophic effects which are mainly mediated through the cAMP/protein kinase A pathway. Here we show that the cell-permeable C2-ceramide selectively blocks PACAP-activated cAMP production, without affecting phosphoinositide breakdown. Thus by blocking the neuroprotective cAMP signalling pathway, C2-ceramide will reinforce its direct death-inducing signalling. We found that a reactive oxygen species scavenger reversed the C2-ceramide effect and that H2O2 mimicked it. Together these data indicate that reactive oxygen species (ROS) mediates C2-ceramide-induced cAMP pathway uncoupling. This uncoupling did not involve ATP supply or Galphas protein function but rather adenylate cyclase function per se. Further, the tyrosine phosphatase inhibitors, but not the serine/threonine phosphatase inhibitors, prevent inhibition of cAMP production by ROS. This suggests that H2O2 requires a functional tyrosine phosphatase(s) to block PACAP-dependent cAMP production.

First manifestations of seronegative spondylarthropathy following autologous stem cell transplantation in HLA-B27-positive patients

Two male patients with non-Hodgkin's lymphoma (NHL, follicular NHL, diffuse large B cell NHL, both in 2nd complete remission) and one female patient with acute myeloid leukemia in 1st complete remission developed arthralgias and enthesopathy following autologous stem cell transplantation. In 2/3 patients, sacroiliitis could be demonstrated on X-ray. In both patients, the rheumatic symptoms were classified as manifestations of a spondylarthropathy. All three patients were subsequently shown to be HLA-B27-positive. The patients were successfully treated with non-steroidal anti-inflammatory drugs. The differential diagnosis of joint pain following autologous stem cell transplantation should include HLA-B27-associated spondylarthropathies in addition to the more commonly seen bone and joint pain due to immobilization and medication.

Comparison of seroprevalences of human herpesvirus-6 and -7 in healthy blood donors from nine countries

BACKGROUND AND OBJECTIVES

The purpose of the study was to register antibody prevalences of HHV-7 in various locations of the world in comparison to the closely related HHV-6.

MATERIALS AND METHODS

Sera of healthy blood donors from nine countries in five continents were titered by indirect immunofluorescent assays using HHV-6 infected HSB2 and HHV-7 infected SupT1 cells.

RESULTS

Antibody prevalence for HHV-7 is high (75-98%) in practically all countries except for Northern Japan (44%), with no simple correlation to elevated HHV-6 antibody titers. There were regions of low, intermediate and high mean antibody titers against HHV-7 such as 78.5-91.3 for Belgium, Israel, Japan, USA and Australia, 175.4-182.6 for Mexico and Cologne/Germany, and 389.2 for South Africa for which geographic characteristics may be responsible.

CONCLUSION

HHV-7, similar to HHV-6, is a widespread human herpesvirus with elevated antibody titers in the healthy human population essentially everywhere. The data warrant further studies to evaluate its possible pathologic potential, preferentially in persons with defective immune responses.

Vitamin D: should the supply in the Danish population be increased?

A working group was established to evaluate the need for an increased vitamin D intake in the Danish population. Vitamin D is primarily important for calcium homeostasis, calcium absorption in the intestine and calcium content in bones, and thereby for the strength of the bones. Only a few foods provide vitamin D and the intake in the Danish population is low compared to the recommendation. However, vitamin D is also produced by the skin from solar exposure. How much vitamin D is provided this way is not known but it is said to be the most important source. Measures of vitamin D status and clinical signs of vitamin D status are therefore important when assessing the possible need for increased vitamin D intake. Measures of vitamin D status have shown a low status in the elderly but not in the young. More than 50% of nursing-home residents have low blood vitamin D levels and many have biochemical signs of osteomalacia. Vitamin D deficiency increases the risk of osteoporosis. In Denmark, for instance, 13,000 admissions each year are caused by hip fractures alone, almost all among elderly people. Dark-skinned women often constitute a problem with respect to vitamin D sufficiency because of reduced production from the skin secondary to extensive covering, skin pigmentation and many hours spent indoors. It is concluded that the elderly and dark-skinned (veiled) women will benefit from an increased vitamin D supply. Four strategies to increase vitamin D supply were considered: dietary changes, increased solar exposure, dietary supplements with vitamin D and food fortification with vitamin D. It is concluded that the best solution is to recommend dietary supplements with vitamin D to elderly over 65 years, dark-skinned and veiled women and people who, because of disease, are unable to spend time outdoors.

EMB-30: an APC4 homologue required for metaphase-to-anaphase transitions during meiosis and mitosis in Caenorhabditis elegans

Here we show that emb-30 is required for metaphase-to-anaphase transitions during meiosis and mitosis in Caenorhabditis elegans. Germline-specific emb-30 mutant alleles block the meiotic divisions. Mutant oocytes, fertilized by wild-type sperm, set up a meiotic spindle but do not progress to anaphase I. As a result, polar bodies are not produced, pronuclei fail to form, and cytokinesis does not occur. Severe-reduction-of-function emb-30 alleles (class I alleles) result in zygotic sterility and lead to germline and somatic defects that are consistent with an essential role in promoting the metaphase-to-anaphase transition during mitosis. Analysis of the vulval cell lineages in these emb-30(class I) mutant animals suggests that mitosis is lengthened and eventually arrested when maternally contributed emb-30 becomes limiting. By further reducing maternal emb-30 function contributed to class I mutant animals, we show that emb-30 is required for the metaphase-to-anaphase transition in many, if not all, cells. Metaphase arrest in emb-30 mutants is not due to activation of the spindle assembly checkpoint but rather reflects an essential emb-30 requirement for M-phase progression. A reduction in emb-30 activity can suppress the lethality and sterility caused by a null mutation in mdf-1, a component of the spindle assembly checkpoint machinery. This result suggests that delaying anaphase onset can bypass the spindle checkpoint requirement for normal development. Positional cloning established that emb-30 encodes the likely C. elegans orthologue of APC4/Lid1, a component of the anaphase-promoting complex/cyclosome, required for the metaphase-to-anaphase transition. Thus, the anaphase-promoting complex/cyclosome is likely to be required for all metaphase-to-anaphase transitions in a multicellular organism.

Biomonitoring of environmental polycyclic aromatic hydrocarbon exposure by simultaneous measurement of urinary phenanthrene, pyrene and benzo[a]pyrene hydroxides

A high-performance liquid chromatographic method with fluorescence detection was developed which enables the simultaneous determination of the urinary polycyclic aromatic hydrocarbon metabolites 3-hydroxyphenanthrene, 1-hydroxypyrene and 3-hydroxybenzo[a]pyrene. The method has small solvent consumption because of the use of a microbore RP C18 column and a relatively short run time. Low detection limits of 0.02 nmol/l for 3-hydroxypyrene to 0.19 nmol/l for 3-hydroxybenzo[a]pyrene were attained. In contrast, the detection limits of alpha-naphthol and 9,10-dihydroxy-9,10-dihydrophenanthrene were not adequate for the determination of environmental exposure. The developed method was successfully used for the analysis of urine samples from children.

[Doppler sonography of the short posterior ciliary artery in patients with primary open angle glaucoma]

AIM

The area of primary damage in glaucomas is the optic nerve head. This region is directly supplied by the peripapillary choroid and the short posterior ciliary arteries (SPCA). This study was designed to evaluate the choroidal and SPCA haemodynamics in high tension (HTG) and normal tension (NTG) primary open angle glaucoma patients, as well as in healthy controls (CTL).

METHODS

20 HTG, 12 NTG, and 32 age matched volunteers (CTL) without clinically relevant extracranial stenosis of the carotid arteries were evaluated for ocular pulse amplitude (OPA; OBF-System OBF Labs, UK) and for temporal SPCA peak systolic flow (PSV), enddiastolic flow (EDV), pulsatility (PI) and resistance indices (RI) using a 9 MHz phased array (Elegra Advanced System; Siemens, Germany).

RESULTS

(mean +/- SD): In the control group the PSV (cm/s) of the SPCA was 10.90 +/- 1.53; EDV (cm/s) was 3.24 +/- 0.24, PI was 1.30 +/- 0.39, RI was 0.69 +/- 0.11, OPA (mm Hg) was 2.2 +/- 0.25; IOP (mmHg) was 14.6 +/- 1.5. When compared to CTL matched for age, sex, and refraction, NTG-patients showed the following results: OPA was significantly (p < 0.05) reduced, dopplersonography showed a significant (p < 0.05) reduction in diastolic flow patterns and a significant (p < 0.05) increase in PI and RI. In HTG-patients the parameters investigated where not significantly (p > 0.05) altered.

CONCLUSION

These data suggest reduced haemodynamics in the choroid and in the SPCA of NTG patients, which may contribute to progression of the optic neuropathy. In HTG the Doppler parameters and the OPA are not altered compared with the control group.